Posts Tagged macro

It still is. But I needed to photograph something this weekend. I’ve been head down, working on a lot of research projects of late, and the time to get out and decompress has been hard to find.

Fortunately, one of the things that thrives in wet conditions, is fungi. So between showers on Sunday went out and tried my hand at it. The gear is the a900, a Minolta 100/2.8mm macro lens, and the Sony twin-macro flash. The flash has these convenient extending arms. These allow for more precise placement of the light. With the wet, reflective surfaces of the fungi I also went with the flash diffuers to soften the light.

It’s a subject I’m dabbling with, and here are some of the fungi you can see in the NZ bush at the moment.

Well, I seem to have got off on a classic Minolta lens binge at the moment. Minolta made the first popular auto-focus camera back in 1985, with the Maxxum (or Dynax) 7000. This was followed by a series of new AF lenses for this mount. These replaced the existing manual focus lens (MD or MC).

In the film era, camera companies tended to produce lenses with slightly different characteristics. For Minolta, the thing that made their lenses stand out was the colours. They had a colour fidelity and richness that appealed. If you ever hear some photographer talking about ‘Minolta colours’, that’s what they mean. I’m finding as I do more landscape photogaphy, this is what appeals to me.

As an indication of the lead Minolta built up in the 1980s, they had the first auto-focus 100mm macro lens. This was such a superb design, the modern Sony lens equivalent has made only minor changes to it. I acquired the RS version yesterday (this model went out of production in 1993). I wanted to see how it lasted, so gave it a try with my a900 last night.

These two spider shots are all done in manual mode. I’ve selected both the exposure (shutter speed, aperture) and the flash setting for my twin flash. The first spider I saw was a juvenile nursery-web spider- Dolemedes minor. It was on some pruned back flax.

The second was the nervous and wary Cambridgea sheetweb spider. By this time one of the local cats had come to help me. Despite this not being fully mature, I didn’t need to crop this pic at all.

Well, the good news is that the lens is in near perfect order. Despite its age and who knows, how many owners, this has survived nicely.

The cicadas have been particularly vocal this month. This has been helped by the numbers of them. The local population has exploded. Oddly, the neighbour’s cat had decided they’re good to hunt. Also to eat- the crunchy sounds of a cicada succumbing to the jaws of a domestic cat are interesting.

I’ve got a couple of shots of the ‘green’ species kihikihi wawa Amphipsalta zealandica here.

1. “The Singer” – the wings are blurred as it vibrates the sound.

2. “The Embrace” – the female is clinging to the grass stalk, while the male is err, clinging to the female :)

This time of year you might notice some flies repeatedly shaking their legs. A closer look will show a tiny, pale brown thing attached to the leg. This is actually one of our native pseudoscorpion Thalassochernes tairiensis. What is is doing is hitching a ride on the fly. This is a habit known as phoresy. It’s a way for the animal to get a ride somewhere else. For minute animals unable to cover a lot of ground, phoresy is quite handy.

Pseudoscorpions are an order of arachnids that are widely distributed. As an order, they are on par with spiders or scorpions or harvestmen. Despite being even more widely distributed than scorpions, most people are not aware of them. The reason is simple. These arachnids are tiny and cryptic. They dislike the light and move away from it. They’re usually very small. Most are much less than 2mm long.

They have a number of appealing traits however. The female feeds nymphs a nourishing liquid. They also have small silk glands, which in some families are used to make little domes to protect the female and her nymphs. Despite their pincers and segmented body, they’re not a descendant of scorpions. Their poison apparatus is on a tiny tooth, on one of the fingers of their claw. It’s pretty lethal if you’re a mm long and have 6 legs.

To get these pics I waited for the pseudoscorpion to detach herself. To boost the magnification (the arachnid here is about 2mm long) I attached a 24x Raynox microscope adapter. Then my macro flash (the two small heads of this are much easier to work up close than a ringflash) was attached to boost the shutter speed. I had hoped I could get some shots hand-holding the camera but this was impossible. The depth-of-field was critically narrow and for a moving subject, impossible. So it was then on to the tripod (and thankfully, the geared head).

Even with the 24x magnifier I still couldn’t see the edge of the carapace so a bit of guesswork was involved. At least with the arachnid being blind, I didn’t have to worry about getting the eyes in focus. They have a number of long, sensitive seta (trichobothria) on their claws that are used to locate prey.

Bear in mind with these pics, almost all the detail shown here is invisible to the naked eye.

Trilobites first appeared in the geological column in the Cambrian era (543 to 490 mya). They were an enormously successful group of animals, with some 5000 genera and over 30,000 described species. Many of the trilobites became extinct during the great late Devonian extinction (c 360 mya) . The last of the trilobites became extinct in the even greater Permian-Triassic extinction about 250 mya.

One of the most common trilobites Elrathia kingii is from the mid-Cambrian (c 500mya) and is extremely abundant. While trilobites are extinct, the allied arachnomorphs- the related chelicerates- still persist today. The arachnids are well-known members of the arachnomorph group [1].

Click image for larger sized version

This trilobite is found in bedding planes in high density (up to 500 individuals per square metre) [2] and in different age groups (sizes vary from 4-40mm for complete individuals) [2].

They are found in settled strata (lacking the bioturbation of surface wave action) and were adapted to very low oxygen conditions. This appeared to have been an adaptation that served it well as other trilobites could not compete in such a low oxygen environment. This accounts for both the sediments it is found in, and the lack of competition. Elrathia kingii occur as single species associations of very high density.

References

[1] Cotton, T.J. and Braddy, S.J. (2004). The phyologeny of arachnomorph arthropods and the origin of the Chelicerata, Transactions of the Royal Society of Edinburgh: Earth Sciences, 94, 169-193

This is a spider photo, which I actually took at Singapore Zoo. The novel feature I guess of this photo, is I didn’t have a proper macro lens to make the shot. So this is using a combination of a 70-200/4 lens and a achromatic diopter, with of course, a flash. In effect, I’m having to improvise. Which is a common issue with travel photography.

It is a female and an orbweb spider. The colours and spikes actually make for quite good camouflage.

Blogroll

About SciBlogs

Sciblogs is the biggest blog network of scientists in New Zealand, an online forum for discussion of everything from clinical health to climate change. Our Scibloggers are either practising scientists or have been writing on science-related issues for some time. They welcome your feedback!